In addition, offering an ability to be copied allows for an opportunity for that ability to be verified by the user regardless of the intentions of the player copying
Let's say I don't trust indigo. I give him a crappy ability. Then, I use crappy ability. I then force indigo to confirm that usage. Boom I'm clear.
Conversely if you're scum, it's harmful if you offer an ability, because then your usage will appear in write ups and be scrutinized